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SDR 24/96
SDR 24/96
Metering and Setting Record Levels
A professional analog recorder has meters that indicate 0 VU at a +4 dBu nominal
signal level. Generally you can record peaks 10 to 15 dB above that before
distortion becomes objectionable. This 10-15 dB range above the nominal level is
called “headroom.”
On digital recorder meters, zero represents the full-scale digital signal level, 0
dBFS for short. 0 dBFS is the hottest signal that a digital device can handle, with
no headroom to spare. When a digital signal reaches 0 dBFS for more than a
sample or two, the resulting distortion is uglier than scraping your fingernails
across a chalkboard.
To get the get the best sound from the SDR24/96:
1. Turn ALL INPUT on.
2. Ask the talent to play or sing as loud as they will be performing during the
session. While watching the SDR24/96 meters, adjust the console’s tape
outputs so that the signal peaks cause the red overload indicators to come
on occasionally. Then, back off the tape output level slightly. This insures
the best fidelity and the widest dynamic range in the recorded signal and
leaves you a little headroom to accommodate the talent’s enthusiasm.
Keep the signal levels as high as possible without overload, because
recording at lower levels reduces resolution and dynamic range.
Nonetheless it is always better to be conservative and avoid the risk of
overload than to try squeezing the last ounce of dynamic range from the
signal.
3. Alternately, if you have a tone generator or a sound source with a constant
volume (you can hold down a key on a synth), turn All Input on and send
the tone to all 24 tracks of the console. Adjust the output levels to read 0
VU on analog consoles, or around –20 dBFS on digital consoles. If the
SDR24/96 meters read –15 to –20, you’re in good shape. This leaves
enough headroom for most popular music, but if you’re recording acoustic
music, jazz, classical, or narration, you may want to leave a little more.
When the talent starts to play you may have to make some final tweaks to
get everything just right.
4. After adjusting the tape output levels for each console channel, follow
your console manufacturer’s instructions for setting the console tape
return levels.
With analog I/O, a +22 dBu signal at the SDR24/96
inputs and outputs corresponds to 0 dBFS inside the
SDR24/96. So, if your console has a nominal output level
(0 VU) of +4 dBu, there is 18 dB of headroom before you
hit the maximum record level on the SDR24/96. It also
means that your console must be capable of putting out
at least +22 dBu without distortion so the console
24 TRACK/24 BIT DIGITAL AUDIO RECORDER
242322
21
2019181716151413121110987654321
ALL
INPUT
OL
2
50
4
7
10
15
20
25
30
35
40
+22 dBu
dBu
equivalent
+20
–28 dBu
+18
+15
+12
+7
+2
–3
–8
–13
–18